acpi_toshiba: fix kconfig error

Fix kconfig recursive dependency error in ACPI_TOSHIBA:
it uses both select and depends on for BACKLIGHT_CLASS_DEVICE.

drivers/video/backlight/Kconfig:117:error: recursive dependency detected!
drivers/video/backlight/Kconfig:117:    symbol BACKLIGHT_CLASS_DEVICE is selected by ACPI_TOSHIBA
drivers/platform/x86/Kconfig:490:       symbol ACPI_TOSHIBA depends on LEDS_CLASS
drivers/leds/Kconfig:12:        symbol LEDS_CLASS is selected by BACKLIGHT_ADP8860
drivers/video/backlight/Kconfig:285:    symbol BACKLIGHT_ADP8860 depends on BACKLIGHT_CLASS_DEVICE

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>